In the medical field, radiation image capturing apparatus have widely been used, which apply radiation to a subject and guide the radiation that has passed through the subject to a radiation conversion panel, which captures a radiation image from the radiation. Known forms of radiation conversion panels include a conventional radiation film for recording a radiation image by way of exposure, and a stimulable phosphor panel for storing radiation energy representing a radiation image in a phosphor and reproducing the radiation image as stimulated light by applying stimulating light to the phosphor. The radiation film with the recorded radiation image is supplied to a developing device to develop the radiation image, or the stimulable phosphor panel is supplied to a reading device to read the radiation image as a visible image.
In an operating room or the like, it is necessary to read a recorded radiographic image immediately from a radiation conversion panel after the radiographic image has been captured, for the purpose of quickly and appropriately treating the patient. As a radiation conversion panel that meets such a requirement, a radiation detector has been developed having a solid-state detector for converting radiation directly into electric signals, or converting radiation into visible light with a scintillator and then converting the visible light into electric signals in order to read a detected radiographic image.
When the radiation conversion panel detects radiation and converts the detected radiation into radiographic image information, the radiation conversion panel outputs signals representative of the radiographic image information. Since the signals output from the radiation conversion panel are low in level and susceptible to electromagnetic noise, the quality of radiographic images generated based on such signals tends to be reduced if electromagnetic noise is added to the signals.
Patent Document 1 proposes that capturing of radiographic images and performing wireless communications from a radiation detecting cassette to an external circuit should not be performed at the same time. Patent Documents 2 and 3 propose that a battery and a radiation conversion panel are separated by a partition plate having an electromagnetic shielding capability, which is disposed in a radiation detecting cassette.
If wireless communications are performed between a radiation detecting cassette and an external circuit while a radiographic image of a subject is being captured, then electromagnetic noise, which is caused by the radiation applied to the radiation detecting cassette through the subject, and electromagnetic noise, which is caused by an address signal and a control signal used by the radiation detecting cassette to convert the radiation into radiographic image information, are added to signals that are sent and received by way of wireless communications, tending to lower the quality of the radiographic image information. When electric power is supplied to a battery (power supply) in the radiation detecting cassette by way of wireless communications, if the aforementioned electromagnetic noise is added to the electric power supplied to the battery, then the radiation detecting cassette and the wireless communications means, which are powered by the battery, are likely to malfunction.
According to Patent Document 1, however, no countermeasures are taken to prevent electromagnetic noise from being added to the electric power that is supplied from an external circuit to the battery. According to Patent Documents 2 and 3 as well, no countermeasures are taken to prevent the addition of electromagnetic noise.
Patent Document 4 discloses a radiation detecting cassette for transmitting radiographic image information produced by a radiation detector to an image processing means utilizing a wireless transmission system. A battery disposed in the radiation detecting cassette is wirelessly charged by a contactless battery charger, which is located close to the battery.
When the remaining power level of the battery runs low while the radiation detecting apparatus is being used (while radiographic image information is being captured), it is necessary that the image capturing process be interrupted and that the battery be charged by the contactless battery charger. To charge the battery, the operator places the contactless battery charger near the battery of the radiation detecting cassette, and operates a manual switch or the like. As a result, if the radiation detecting cassette is used during a surgical operation, particularly, the doctor is unable to see the desired radiographic image in real time, and the process for charging the battery is cumbersome and time-consuming.
The radiation detecting cassette, which is wirelessly charged, needs to remain available for charging the battery at all times, or needs to have a switch for initiating charging of the battery. In the former case, wasteful power consumption and malfunctions are likely to occur. In the latter case, the process is cumbersome, and further, the battery will not be charged if the operator forgets to operate the switch.
Patent Document 4 also discloses a technique for charging a battery, in which a power cable is connected to the battery while the battery is dismounted and connected to an external battery charger.
Radiographic image information generated by the radiation detector is transmitted to the image processing means by way of wireless communications. Such radiographic image information, which is transmitted by wireless communications, is susceptible to radio disturbance and noise. When the radiographic image information suffers from radio disturbance, radiographic images generated thereby may not appropriately be displayed.
According to Patent Document 4, furthermore, inasmuch as the radiation detecting cassette depends only on the battery for energization thereof, if the remaining power level of the battery runs too low while the radiation detecting apparatus is being used (while radiographic image information is being captured), the image capturing process must be interrupted in order to charge the battery using the contactless battery charger. As a result, if the radiation detecting cassette is used during a surgical operation, particularly, the doctor is unable to see desired radiographic images in real time.
Cables that may be connected to the radiation detecting cassette should desirably be as minimal as possible, in view of facilitating handling thereof in an operating room or the like.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-210444
Patent Document 2: Japanese Laid-Open Patent Publication No. 2002-214729
Patent Document 3: Japanese Laid-Open Patent Publication No. 2003-121553
Patent Document 4: Japanese Laid-Open Patent Publication No. 2001-224579